The Ionia "Volcano"

Clark's hot bluff may not have been this one. In a 2011 article in We Proceeded On, the Lewis and Clark Trail Heritage Foundation's journal, geologist John W. Jengo worked from a reconstructed 1804 river channel and proposed a bluff several miles upriver, west of today's Newcastle-Vermillion bridge, between the mouth of Ames Creek and a former mouth of Lime Creek near the Cedar-Dixon county line. The Missouri ran at its foot in 1804, while the Ionia bluff stood about a mile back. The same Carlile shale that holds the heat-making minerals at Ionia is exposed there.

What the plaque says

The Ionia "Volcano" On August 24, 1804, the Lewis and Clark Expedition, traveling up the Missouri River, passed a bluff about 180 to 190 feet high. Clark wrote that it appeared to have been on fire and was still very hot. He also detected signs of coal and what looked like cobalt. Later fur traders frequently noticed dense smoke and fire in this region. In 1839, J. N. Nicollet attempted to prove that these phenomena were not of volcanic origin. Nicollet theorized that the decomposition of beds of iron pyrites in contact with water resulted in a heat capable of igniting other combustible materials. Unaware of this explanation, early settlers con- tinued to fear the "Ionia volcano," which took its name from the once flourishing town of Ionia, located northeast of present-day Newcastle. An earthquake in 1877 aroused new fears of an impending volcanic eruption. In 1878, the Missouri River undermined the bluffs and a large section of the "volcano" fell into the river. The same flood nearly destroyed the town of Ionia. "Volcano" stories died out soon after the Ionia post office was discontinued in 1907. Newcastle Community Betterment Committee Historical Land Mark Council

Where it stands

Worth the stop nearby

• Ponca State Park — 9.2 mi
  Oak ravines and bluffs at the downstream end of the Missouri's last unchannelized reach in Nebraska, with a three-state overlook and the river's resource and education center.
• National Music Museum — 9.4 mi
  One of the great collections of musical instruments in the world, on a college campus in a prairie town, built around a band teacher's thousands of horns, fiddles and curiosities.
• Spirit Mound Historic Prairie — 16 mi
  A lone hill north of Vermillion that Lewis and Clark walked to on a scorching day in 1804, now one of the few places left where you can stand exactly where they stood.

More markers nearby

• First Permanent Schoolhouse in Dakota Territory — 9.0 mi
• Grand Officers — 9.0 mi
• Andrew Lee — 9.3 mi
• Bruyer Church — 9.3 mi